The present invention relates to siloxane oligomers, a process for their production as well as their use.
It is known to employ silanes as coupling agents. Thus, aminoalkyltrialkoxysilanes, methacryloxyalkyltrialkoxysilanes, polysulfanalkyltrialkoxysilanes, as well as mercaptoalkyltrialkoxysilanes are used as coupling agents between inorganic materials (e.g. glass fibres, metals, oxidic fillers) and organic polymers (e.g. thermosetting plastics, thermoplastic materials, elastomers) and/or as crosslinking agents and surface modification agents.
These coupling or bonding agents form bonds with the filler as well as the elastomer and thereby produce a good interaction between the filler surface and the elastomer. They reduce the viscosity of the mixture and facilitate the dispersion of the filler.
Furthermore it is known that the use of commercially available silane coupling agents (DE 22 55 577) with three alkoxy substituents on the silicon atom leads to the release of considerable amounts of alcohol during the mixing process.
This amount of alcohol can be reduced if corresponding siloxane oligomers are used instead of monomeric silanes. Siloxane oligomers and siloxane co-oligomers produced by condensation and co-condensation of silanes are described in EP 0 518 057 B1 and in EP 0 652 245 B1.
Disadvantages of the known siloxane oligomers are                the absence of functionalized alkyl groups, which are necessary for subsequent chemical reactions, and        the complicated process for the production of the alkoxysiloxanes by reacting the corresponding chlorosilanes with alcohol followed by removal of the alcohol in the oligomerization or co-oligomerization with other alkoxysilanes.        
An object of the present invention is to produce siloxane oligomers having functionalized alkyl groups.